CN111664060A - Offshore wind turbine foundation anti-scouring structure - Google Patents

Abstract

The invention provides an anti-scour structure for a foundation of an offshore wind turbine, comprising an annular pile skirt sleeved on the outside of the pile foundation and fixed on the seabed surface, the annular pile skirt includes an installation hole for the pile foundation to pass through, and the installation hole is formed by the installation hole. A scour surface with a gradually decreasing height extending to the seabed surface and a buffer surface provided at the connection between the scour surface and the seabed surface. The anti-scour structure for the foundation of an offshore wind turbine provided by the present invention fits the gradient of the seawater velocity change generated by the ocean current or the tide through the inclined surface provided with the scour surface and the buffer surface on the annular pile skirt, so that the ocean current or the tide reaches the annular surface. The speed on the pile skirt is basically the same, which can maximally weaken the ocean current to generate the vortex in front of the pile near the pile foundation and avoid the scour pit formed by the vortex; the anti-scour structure provided by the present invention has the advantages of simple structure, easy processing and relatively low construction cost. Low cost, easy maintenance in the later period, good anti-scour effect, ensuring the bearing capacity of the pile foundation and the reliability of the fan operation.

Description

A foundation anti-scour structure for offshore wind turbines

technical field

The invention relates to the technical field of marine engineering structures, in particular to a foundation anti-scour structure for offshore wind turbines.

Background technique

The offshore wind resources are abundant, the wind speed changes less with height, the turbulence intensity is low, the sea level friction is small, the fatigue load acting on the wind turbine is also small, and the offshore wind power generation is disturbed by noise, birds, and electromagnetic waves. Smaller, and at the same time can not occupy land resources. Therefore, offshore wind power has become the fastest growing green energy technology in the world.

Due to the obstruction of the pile foundation and the influence of the velocity gradient of the ocean current, scouring is easy to occur around the pile foundation built at sea, taking away the sediment around the pile foundation, resulting in the reduction of the bearing capacity of the pile body, the inclination of the foundation, and even the serious collapse of the foundation as a whole. as a result of.

In order to improve the problem of scouring of offshore wind turbine foundation piles, the existing foundations have the following practices:

1. Put concrete or lay sand and gravel within a certain range around the pile foundation. The rigidity of the concrete after solidification is large, which can ensure that the scouring will not affect the pile foundation during the service life, but the concrete is put in a large area and the cost is high. , and later maintenance is also more difficult; while laying sand and gravel to form a scouring surface has a better anti-scour effect in a short time, but there is inevitably a gap between the sand and gravel. The sediment will still be washed away, and the stone will be destroyed, causing the stone to sink into the sediment layer, resulting in weakened protection. In order to maintain the anti-scour effect, it is necessary to continuously put sand and gravel for maintenance, resulting in higher maintenance costs in the later period.

2. Set up an anti-scour structure with a bottom sill on the pile foundation, reduce the flow rate of the bottom ocean current through the stepped structure of the bottom sill, avoid the bottom flow rate from scouring the pile foundation, and use the stepped structure of the bottom sill to destroy the ocean current on the pile foundation. Horseshoe vortex formed nearby. However, in the long-term use of the anti-scour structure with the sill structure, the overflow plate set above the sill will promote the carrying of sediment and silt, causing the accumulation of sand and gravel in the sill below, causing the stairs to rise. The shape of the structure disappeared, so that it could not play the role of destroying the formed horseshoe vortex.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problems of high investment cost and higher maintenance cost in the existing plan of using concrete or sand and gravel to lay the foundation anti-scour structure of offshore wind turbines. In the structure, sand and gravel are easily deposited in the bottom sill, resulting in the disappearance of the stepped structure of the bottom sill and the disadvantage that it cannot play the role of destroying the horseshoe vortex formed by the ocean current.

The technical solution adopted by the present invention to solve the technical problem is as follows: an anti-scour structure for the foundation of an offshore wind turbine, comprising an annular pile skirt sleeved on the outside of the pile foundation and fixed on the seabed surface, the annular pile skirt includes a The installation hole penetrated by the pile foundation, the scouring surface extending from the installation hole to the seabed surface with a gradually decreasing height, and the buffer surface arranged at the connection between the scour surface and the seabed surface.

Further, the lower diameter of the annular pile skirt is 3-4 times the outer diameter of the pile foundation.

Further, a first included angle is formed between the scour surface and the seabed surface, and a second included angle is formed between the buffer surface and the seabed surface, and the second included angle is greater than the first included angle. The included angle and the second included angle is less than 90°.

Specifically, the first included angle is greater than or equal to 13°.

Further, the anti-scour structure further includes at least two spoilers fixed on the annular pile skirt, the spoilers are vertically arranged perpendicular to the scour surface, and horizontally It is arranged perpendicular to the outer circumferential surface of the pile foundation.

Specifically, the height of the highest point of the spoiler from the seabed surface is 0.7-1 times the outer diameter of the pile foundation.

Specifically, the length of the spoiler in the radial direction of the annular pile skirt is 1-2.5 times the outer diameter of the pile foundation.

Specifically, the side surface of one side of the spoiler is in contact with the outer circumferential surface of the pile foundation.

Specifically, six spoilers are uniformly distributed along the circumferential direction on the scouring surface.

Further, each spoiler plate is provided with at least one spoiler hole, and the spoiler hole is a through hole passing through the spoiler plate.

The beneficial effect of the anti-scour structure for the foundation of the offshore wind turbine provided by the present invention is that an annular pile skirt is arranged at the bottom of the pile foundation, and the annular pile skirt is provided with a scour surface and a buffer surface, and the slope of the scour surface and the The slope of the buffer surface is in line with the gradient of seawater velocity changes generated by ocean currents or tides, so that the speed of ocean currents or tides reaching the annular pile skirt is basically the same, which can minimize the current or tides to generate vortices near the pile foundation. , to avoid the scour pit formed by the vortex; at the same time, a spoiler is also set on the annular pile skirt to increase the resistance around the pile foundation, so that the vortex generation direction perpendicular to the pile foundation is separated, the flow rate is reduced, and the dispersed vortex is achieved. The combined action of the annular pile skirt and the spoiler provides a better anti-scour effect for the pile foundation; the anti-scour structure provided by the present invention has the advantages of simple structure, easy processing, low construction cost, and later maintenance. It is convenient to prevent the pile foundation from being scoured by eddy currents by restraining the flow rate of ocean currents or tides around the pile foundation, so as to ensure the bearing capacity of the pile foundation and the reliability of the fan operation.

Description of drawings

Fig. 1 is a three-dimensional schematic diagram of the annular pile skirt in the foundation anti-scour structure for offshore wind turbines provided by the first embodiment of the present invention;

Figure 2 is a full cross-sectional view of an annular pile skirt in a foundation anti-scour structure for offshore wind turbines provided by the first embodiment of the present invention;

3 is a schematic diagram of an offshore wind turbine foundation anti-scour structure installed on a pile foundation provided by the first embodiment of the present invention;

4 is a full cross-sectional view of an annular pile skirt in a foundation anti-scour structure for an offshore wind turbine provided by the second embodiment of the present invention.

In the picture: 100, 100'-anti-scour structure, 10, 10'- annular pile skirt, 11-installation hole, 12-scour surface, 13-buffer surface, 20-spoiler, 21-first side, 22 -Second side, 23-spoiler hole, 200-pile foundation, 300-seabed surface, D-pile foundation outer diameter, D1-lower diameter of annular pile skirt, H1-height of spoiler from seabed surface , L1 - the length of the spoiler, L2 - the distance between the spoiler and the buffer surface, α - the first angle, β - the second angle.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Referring to FIGS. 1-3 , it is an anti-scour structure 100 for a foundation of an offshore wind turbine provided by the first embodiment of the present invention. The anti-scour structure 100 is arranged at the bottom of the pile foundation 200 of the offshore wind turbine, and the anti-scour structure 100 is used to maximize the Therefore, the generation of vortex in front of the pile foundation 200 is reduced, the formation of scour pits at the bottom of the pile foundation 200 is effectively prevented, the bearing capacity of the pile foundation 200 on the seabed surface 300 is ensured, and the inclination of the pile foundation 200 is prevented.

Further, as shown in FIG. 3 , an anti-scour structure 100 for an offshore wind turbine foundation provided in the first embodiment of the present invention includes an annular pile skirt 10 sleeved on the outer side of the pile foundation 200 and fixed on the seabed surface 300 ; At least two spoilers 20 are fixed to the annular pile skirt 10 . In this embodiment, as shown in FIG. 1 , the annular pile skirt 10 is provided with six spoilers 20 uniformly distributed along the circumferential direction of the annular pile skirt 10 . The anti-scour structure 100 and the annular pile skirt 10 can meet the velocity gradient of the ocean current or the tidal flow at the pile foundation 200, so that the ocean current is almost stagnant. The vortex flow passing through the spoiler 20 not only promotes the separation of the flow directions of the vortex flow, but also consumes the flow of the vortex around the pile foundation 200 to achieve the purpose of dispersing the vortex.

Specifically, as shown in FIG. 2 , the annular pile skirt 10 includes an installation hole 11 through which the pile foundation 200 can pass, a scour surface 12 extending from the installation hole 11 to the seabed surface 300 and gradually decreasing in height, and a scour surface 12 provided on the scour surface. The buffer surface 13 at the connection between the surface 12 and the seabed surface 300 . The annular pile skirt 10 is sleeved on the outer circumferential surface of the pile foundation 200 and is located at the connection between the pile foundation 200 and the seabed surface 300 . The diameter of the mounting hole 11 is determined by the machining accuracy and the mounting accuracy. On the premise of ensuring machining accuracy and installation accuracy, the diameter of the installation hole 11 is equal to the outer diameter D of the pile foundation. With the difference in machining accuracy and installation accuracy, the diameter of the installation hole 11 is 10mm-20mm larger than the outer diameter D of the pile foundation. In this embodiment, as shown in FIG. 2 , the annular pile skirt 10 is disposed on the seabed surface 300 in a conical structure, and the annular pile skirt 10 has two inclined surfaces with different angles, facing the outer circumference of the pile foundation 200 . The scouring surface 12 that diverges outwards and the buffer surface 13 that radiates outward from the scouring surface 12 . The heights of the buffer surface 13 and the scouring surface 12 are gradually raised upward from the seabed surface 300 . In the anti-scour structure 100 provided by the present invention, it is precisely through the two-segment slope of the scouring surface 12 and the buffer surface 13 on the annular pile skirt 10 that the velocity gradient of the ocean current that can collide around the pile foundation 200 is basically matched. , so that the ocean current can almost reach the annular pile skirt 10 from top to bottom at the same time, thus playing the role of synchronously restraining the flow of the ocean current, thereby maximally weakening the vortex in front of the pile generated at the pile foundation 200 . At the same time, the height of the scouring surface 12 gradually decreases from top to bottom, so that the ocean current that first reaches the pile foundation 200 from above generates resistance when it flows downward and is not easy to flow downward, thereby reducing the downward impact force of the vortex in front of the pile. , it is possible to avoid the generation of a pile front pit at the annular pile skirt 10 due to the influence of ocean currents or tides. In the foundation anti-scour structure 100 for an offshore wind turbine provided by the present invention, the scouring surface 12 and the buffer surface 13 on the annular pile skirt 10 are both inclined surface designs, and in the process of long-term use, there will be no accumulation of sand and gravel. The problem of failure will not cause the problem of sinking due to long-term use, and the maintenance cost in the later period is low.

Further, as shown in FIG. 2 , the lower diameter D1 of the annular pile skirt 10 is 3-4 times the outer diameter D of the pile foundation. The annular pile skirt 10 is a rigid structure resistant to seawater scouring. In the first embodiment provided by the present invention, the annular pile skirt 10 is a solid structure, which can ensure the scouring surface 12 and the buffer surface 13 to the greatest extent. Stiffness and stability, avoiding the deformation of the scour surface 12 and the buffer surface 13 due to the impact of ocean currents. The size of the lower diameter D1 of the annular pile skirt 10 is determined by the velocity gradient of the ocean current or the tide where the pile foundation 200 is installed. The greater the change of the velocity gradient formed by the ocean current from top to bottom, the smaller the lower diameter D1 of the corresponding annular pile skirt 10 . The smaller the change of the velocity gradient formed by the ocean current from top to bottom is, the larger the lower diameter D1 of the corresponding annular pile skirt 10 is.

Further, as shown in FIG. 2 , a first angle α is formed between the scouring surface 12 of the annular pile skirt 10 and the seabed surface 300 , and a second angle β is formed between the buffer surface 13 and the seabed surface 300 , The second included angle β is greater than the first included angle α and the second included angle β is smaller than 90°. The first angle α formed between the scour surface 12 and the seabed surface 300 is greater than or equal to 13°. That is, α≥13°, so that the scouring surface 12 can conform to the velocity gradient of the ocean current in the height direction, so that the scouring surface 12 can effectively restrain the flow of the ocean current. At the same time, α<β<90°, so that there can be a certain transition between the buffer surface 13 and the scour surface 12 , and the buffer surface 13 can better satisfy the velocity gradient change of the ocean current near the seabed surface 300 . The specific parameters of the first included angle α and the second included angle β are determined by the marine environmental conditions in which the pile foundation 200 is installed. The specific inclinations of the scour surface 12 and the buffer surface 13 are determined by measuring the marine environment where the pile foundation 200 is installed in advance.

Further, the anti-scour structure 100 provided by the present invention further includes at least two spoilers 20 fixed on the scour surface 12 , the arrangement of the spoilers 20 can further prevent the vortex in front of the pile at the pile foundation 200 flow. The number and manner of setting the spoiler 20 are determined by the environment where the pile foundation 200 is installed. The spoiler 20 may be uniformly distributed along the circumferential direction of the annular pile skirt 10 as shown in FIG. 1 . In this embodiment, six spoilers 20 are evenly distributed along the circumferential direction on the scouring surface 12 of the annular pile skirt 10 . Of course, the distribution of the spoiler 20 may also be more distributed on the scouring surface 12 of the annular pile skirt 10 on the side where ocean currents are likely to occur, and the other side correspondingly reduced in distribution. Specifically, the distribution number of the spoiler 20 is also determined by the flow velocity of the vortex in front of the pile that can be generated at the pile foundation 200 . If the flow velocity of the vortex in front of the pile is fast, the number of spoilers 20 can be increased accordingly, and if the flow velocity is slow, at least two can be set to further prevent the flow of the vortex. Generally speaking, 2-10 spoilers 20 can be distributed on the annular pile skirt 10 to prevent the flow of the vortex.

Specifically, the spoiler 20 provided in the anti-scour structure 100 provided by the present invention is a steel plate with a certain thickness, and the spoiler 20 can be integrally formed with the annular pile skirt 10, or it can be welded or It is fixed on the scouring surface 12 of the annular pile skirt 10 by means of riveting, screw connection and the like. When fixing the spoiler 20 , it is only necessary to ensure that the spoiler 20 is arranged perpendicular to the scouring surface 12 in the vertical direction and perpendicular to the outer circumferential surface of the pile foundation 200 in the horizontal direction. The spoilers 20 are vertically arranged perpendicular to the scouring surface 12 , that is, each spoiler 20 is vertically arranged perpendicular to the seabed surface 300 , and adjacent spoilers 20 are parallel to each other. The spoiler 20 is arranged perpendicular to the outer circumferential surface of the pile foundation 200 in the horizontal direction, so that the spoiler 20 reduces the vorticity of the vortex perpendicular to the pile foundation 200, so that the vortex flow flows through the spoiler 20 in the Separation occurs in the direction, and part of the vortex surrounding the pile foundation 200 will be carried away by the external ocean current, and part will be consumed by impact through the arrangement of the spoiler 20 . The purpose of further dispersing the vorticity of the pile front vortex around the pile foundation 200 is achieved by disposing the spoiler 20 on the annular pile skirt 10 .

Specifically, as shown in FIG. 2 , the height H1 of the highest point of the spoiler 20 from the seabed surface 300 is 0.7-1 times the outer diameter of the pile foundation 200 . The height of the sum of the spoiler 20 and the annular pile skirt 10 is the height H1 from the highest point of the spoiler 20 to the seabed surface 300 , and the height H1 is determined by the surrounding marine environment at the pile foundation 200 . The height of the spoiler 20 is basically the same as the height of the annular pile skirt 10. If the height H1 of the highest point of the spoiler 20 from the seabed surface 300 is larger, the thickness and stiffness of the spoiler 20 need to be increased correspondingly. Deformation of the spoiler 20 due to the impact of ocean currents is avoided. If the height H1 of the highest point of the spoiler 20 from the seabed surface 300 is small, the effect of preventing the vortex around the pile foundation 200 cannot be achieved.

Specifically, as shown in FIG. 2 , the length L1 of the spoiler 20 in the radial direction of the annular pile skirt 10 is 1-2.5 times the outer diameter D of the pile foundation. If the length L1 of the spoiler 20 is too large, the requirements for the thickness of the spoiler 20 are higher, that is, the rigidity of the spoiler 20 is required to be too large, resulting in an increase in the weight and cost of the spoiler 20 . The length L1 of the spoiler 20 is too small, the length L1 provided on the scour surface 12 is insufficient, and the effect of blocking the flow of the ocean current around the pile foundation 200 is not sufficient. Therefore, the length L1 of the spoiler 20 is 1-2.5 times the outer diameter D of the pile foundation, and the specific value is determined by the installation environment of the pile foundation 200 .

Further, as shown in FIGS. 2 and 3 , the side surface 21 on one side of the spoiler 20 is in contact with the outer circumferential surface of the pile foundation 200 , and the distance L2 between the side surface 22 on the other side of the spoiler 20 and the buffer surface 13 is 0-0.5 times the length L1 of the spoiler 20 . That is, the spoiler 20 may extend from the outer circumferential surface of the pile foundation 200 to the seabed surface 300 , or may be shortened to only be provided on the scour surface 12 as required. It is only necessary to ensure that the length L1 of the spoiler 20 can cover the vortex flow at the outer circumference of the pile foundation 200 .

Further, as shown in FIG. 1 , each spoiler 20 is provided with at least one spoiler hole 23 , and the spoiler hole 23 is a through hole passing through the spoiler 20 . The spoiler hole 23 may be a plurality of through holes distributed on the spoiler plate 20 according to a certain rule, or may be a through hole provided on the spoiler plate 20 as shown in FIG. 1 . The arrangement of the disturbing holes 23 further plays the role of disturbing the flow direction and flow speed of the vortex, and the arrangement manner and arrangement quantity thereof are not specifically limited.

Referring to Fig. 4, it is a foundation anti-scour structure 100' for an offshore wind turbine provided by the second embodiment of the present invention. The difference between the second embodiment provided by the present invention and the first embodiment is that on the premise that the overall rigidity of the scouring surface and the buffer surface of the annular pile skirt 10 ′ will not be deformed by the scour of the ocean current, the annular pile The interior of the skirt 10' can be configured as a hollow structure. The hollow structure of the annular pile skirt 10' can reduce the weight of the entire anti-scour structure 100', and reduce the cost as much as possible on the premise of ensuring the anti-scour effect of the anti-scour structure 100'.

An anti-scour structure 100 (100') for an offshore wind turbine foundation provided by the present invention is provided with an annular pile skirt at the bottom of the pile foundation 200. The annular pile skirt is provided with a scour surface 12 and a buffer surface 13. The slope of the surface 12 and the slope of the buffer surface 13 are in line with the gradient of the sea water velocity change generated by the ocean current or tide, so that the speed of the sea water generated by the ocean current or the tide reaching the annular pile skirt 10 is basically the same, so that the ocean current can be weakened to the greatest extent. Or the tide will generate vortex in front of the pile near the pile foundation 200 to avoid the scour pit formed by the vortex; at the same time, a spoiler 20 is also provided on the annular pile skirt to increase the resistance around the pile foundation 200, so that it is perpendicular to the pile. The vortex generation direction of the foundation 200 is separated, the flow velocity is reduced, and the purpose of dispersing the vorticity is achieved; the joint action of the annular pile skirt 10 and the spoiler 20 provides a better anti-scour effect for the pile foundation 200; The anti-scour structure has the advantages of simple structure, easy processing, low construction cost, and convenient maintenance in the later period. By restraining the flow rate of ocean current or tide around the pile foundation 200, the pile foundation 200 is prevented from being scoured by eddy currents, and the bearing capacity and operation reliability of the pile foundation 200 are guaranteed. , prolong the service life of the pile foundation 200.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. Inside.

Claims (10)

1. An offshore wind turbine foundation anti-scour structure is characterized in that it comprises an annular pile skirt that is sleeved on the outside of the pile foundation and is fixed on the seabed surface, and the annular pile skirt includes an annular pile skirt that can be worn by the pile foundation. An installation hole, a scouring surface whose height gradually decreases from the installation hole to the seabed surface, and a buffer surface provided at the connection between the scour surface and the seabed surface. 2 . The anti-scour structure for offshore wind turbine foundation according to claim 1 , wherein the lower diameter of the annular pile skirt is 3-4 times the outer diameter of the pile foundation. 3 . 3 . The anti-scour structure for an offshore wind turbine according to claim 1 , wherein a first included angle is formed between the scour surface and the seabed surface, and the buffer surface and the seabed surface A second included angle is formed therebetween, the second included angle is greater than the first included angle and the second included angle is less than 90°. The foundation anti-scour structure for an offshore wind turbine according to claim 3, wherein the first included angle is greater than or equal to 13°. 5. The anti-scour structure for offshore wind turbine foundation according to claim 1, wherein the anti-scour structure further comprises at least two spoilers fixed on the annular pile skirt, the spoiler The plate is arranged perpendicular to the scouring surface in the vertical direction, and is arranged perpendicular to the outer circumferential surface of the pile foundation in the horizontal direction. 6 . The anti-scour structure for offshore wind turbine foundation according to claim 5 , wherein the height of the highest point of the spoiler from the seabed surface is 0.7-1 of the outer diameter of the pile foundation. 7 . times. 7 . The anti-scour structure for offshore wind turbine foundation according to claim 5 , wherein the length of the spoiler in the radial direction of the annular pile skirt is 1-2.5 times the outer diameter of the pile foundation. 8 . 8 . The anti-scour structure for the foundation of an offshore wind turbine according to claim 7 , wherein the side surface of one side of the spoiler is in contact with the outer circumferential surface of the pile foundation. 9 . 9 . The foundation anti-scour structure for an offshore wind turbine according to claim 5 , wherein six spoilers are uniformly distributed along the circumferential direction on the scour surface. 10 . 10. The anti-scour structure for offshore wind turbines according to any one of claims 5 to 9, wherein at least one spoiler hole is provided on each spoiler plate, and the spoiler hole is a perforation hole. A through hole provided in the spoiler.

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